Known in the prior art is a percussion-type device for making holes in soil (cf. Pneumatic Percussion-Type Devices and Machines for Driving Light Construction Elements in Soil by Kostylev A. D., Gurkov K. S., Smolyanitsky B. N., Novosibirsk, 1980, Publishing House "Nauka", p. 9), comprising a body, a percussion member and an air distributing sleeve. The air distributing sleeve is connected to the body by means of a threaded bushing with a lock washer. In the process of operation of this device, it becomes necessary to disassemble the body-to-threaded bushing joint (for maintenance, repair, etc.); as a result, the lock washer gets out of order after two-three disassembly operations.
Also known to the prior art is a percussion-type device for making holes in soil (cf. Pneumatic Percussion-Type Devices and Machines for Driving Light Construction Elements in Soil by Kostylev A. D., Gurkov K. S., Smolyanitsky B. N., Novosibirsk, 1980, Publishing House "Nauka", p. 10), comprising a body, a percussion member and an air distributing sleeve. The air distributing sleeve is connected to the body by means of a threaded bushing. The body-to-threaded bushing joint is fixed by mating of conical surfaces of the body and threaded bushing.
In the service period this device operates in a percussion-vibration mode due to which the threaded joint works loose and operates for some time in the loosened condition which leads to failure of the thread.
Besides, substantial radial forces are developed in the body portion where the cone is made which cause destruction of the body.
In addition this device features a low operating reliability as unscrewing of the threaded bushing during operation of the device causes axial displacement of the air distributing sleeve which disturbs the operating cycle of the device. Axial displacement of the air distributing sleeve (rearwards) causes an advanced exhaust of compressed air into the front chamber of the device. This air brakes the percussion member before it strikes a blow which reduces the energy of the blow and consequently decreases the capacity of the device. During the return motion of the percussion member the front chamber of the device is kept longer under the pressure (the front edge of the air distributing sleeve is displaced rearwards). Therefore, a greater quantity of the kinetic energy is imparted to the percussion member and after the retarded exhaust of compressed air from the front chamber (the rear edge of the air distributing sleeve is also displaced rearwards) the percussion member covers a greater distance (the braking distance of the percussion member increases) and may administer blows at the front end of the threaded bushing. Thus, due to unscrewing of the threaded bushing the percussion member administers blows both at the front and rear portions of the device, thereby disturbing the mode of operation of the device which may lead to a drop in the penetration rate and cause a complete stop of the device.
The invention is aimed at providing a device for making holes in soil, wherein the design embodiment of a threaded bushing will provide stabilization of the air distributing sleeve edges in the process of the device operation in the soil.